Tension lockup for printing plates



June 1, 1954 c, s. 2,679,802

TENSION LOCKUP FOR PRINTING PLATES 2 Sheets-Sheet 1 Filed Oct. 21 1950 W I I June 1, 1954 c. s. CRAFTS TENSION LOCKUP FOR PRINTING PLATES 2 Sheets-Sheet 2 Filed Oct. 21 1950 Patented June 1, 1954 TENSION LOCKUP FOR PRINTING PLATES Curtis S. Crafts, Oak Park, 111., assignor to The Goss Printing Press Company, Chicago, Ill., a corporation of Illinois Application October 21, 1950, Serial No. 191,465

11 Claims. (Cl. 101-378) The present invention pertains generally to rotary printing presses and more specifically to a novel and improved arrangement for securing to a plate cylinder one or more arcuate printing plates of the general type disclosed in my prior Patent No. 2,474,889, issued July 5, 1949.

The use of modern rotary presses for multicolor printing necessitates the provision of an especially accurate means for securing the printing plates to their plate cylinders. Such means must have incorporated therein a precision adjustment arrangement for effecting color registration and which permits each printing plate to be adjustably positioned both circumferentially and laterally of the plate cylinder. Where the plates are secured by means of a tension lockup arrangement, lateral adjustment becomes rather a simple matter, but precise circumferential adjustment raises a problem. This is due to the fact that the lockup means engages both the leading and trailing arcuate end portions of each plate and places the same under considerable tension. Accordingly, it is an object of the present invention to provide a novel and improved tension lockup arrangement for securing arcuate printing plates to a plate cylinder and wherein the plates will be susceptible of positive circumferential adjustment with nicety and precision. A related object is to provide a tension lockup which will readily permit lateral adjustment of the plates.

Another object is to provide a tension lockup of the type set forth and which permits individual adjustment of each plate in both the circumferential and lateral directions.

A more detailed object is to provide a tension lockup of the foregoing character which will be of simple, economical and substantially foolproof construction.

Other objects and advantages will become apparent as the following description proceeds, taken" in connection with the accompanying drawings, wherein:

Figure 1 is a transverse sectional view through the end portion of an illustrative plate cylinder equipped with one form of tension lockup embodying the present invention.

Fig. 2 is a fragmentary view similar to Fig. 1 but showing the lockup in a different condition of adjustment.

Fig. 3 is a view similar to Fig. 1 but showing an illustrative plate cylinder equipped with a slightly modified form of tension lockup also embodying the present invention.

Referring more specifically to the drawing, there is shown in Fig. 1 an illustrative plate cylinder I equipped with a tension lockup embodying the present invention. The cylinder II) is fixed to a supporting shaft I l running axially and extending beyond the ends thereof. Seated on the periphery of the cylinder ID are one or more pairs of arcuate printing plates I2, each such plate in this instance being of the type disclosed in my prior Patent No. 2,474,889, supra. Briefly, each of the plates I2 is of substantially segmental form, having a convex face which defines a printed signature and a concave face which seats against the surface of the cylinder II). On its concave face, the leading and trailing end portions of the plate I2 are provided with a plurality of axially elongated pockets I 4. Each of the latter has a smoothly arched contour I5 terminating in an undercut end wall I6 which coacts with an appropriate gripping mechanism I8 carried by the cylinder I0.

In the present instance, the illustrative cylinder I!) under consideration herein happens to be equipped with one pair of gripping mechanisms I8 of the toggle type for each diametrically opposed pair of printing plates I 2. Since such gripping mechanisms are identical, a description of one will sufiice for all. Referring in particular to the right-hand half of Fig. 1, it will be perceived that the mechanism I8 there shown comprises a pair of axially extending rock shafts I9 journaled in the body of the cylinder I0 and separated from each other by a relatively large obtuse angle somewhat less than Each of the shafts I 9 has rigidly fixed thereto a series of axially spaced rocker arms corresponding in numher and position to the pockets I4 in the adjacent end portion of the plate I2. For purposes of description, the rocker arms on one of the shafts I9 will be designated by the numeral 20A while those on the other shaft will be designated by the numeral 20B. Each of the rocker arms 26A, 20B is fashioned with a gripping finger of appropriate contour to enter one of the pockets I l and to abuttingly engage the undercut end wall N5 of the latter. To facilitate such engagement, the finger 2! has a gripping surface 22 substantially complemental to the undercut end wall I 6 of the pocket. Each of the shafts I9, together with its rocker arms 20A or 20B and gripping fingers ZI, has a fully disengaged position which may be defined by a mechanical stop 24 fixed to the body of the cylinder I0. In this position, illustrated in the right-hand half of Fig. 1, the gripping fingers 2| are withdrawn to positions substantially coincident with or slightly within the outer peripheral surface of the cylinder IU. For the purpose of shifting the gripping mechanism I8 from a fully disengaged position to a fully engaged position, illustrated in the left-hand half of Fig. 1, the end rocker arms 20A, 20B of each pair of the shafts I9 are pivotally connected as at 25 with a pair of arcuate toggle links 25. The latter, in turn, have their opposite ends connected by a common pivot 28 to an adjusting nut 29.

Disposed in threaded engagement with the nut 29 is a drawbolt 30 which can be turned by means of an adjusting head 31 to shift the nut 29 axially of the bolt 30.

Means is provided for locating each of the plates l2 in various positions of circumferential adjustment as an incident to the operation of its gripping mechanism. This is accomplished by the remarkably simple expedient of utilizing an adjustable stop abutment means to define the fully engaged position of the gripping mechanism. Turning once more to Figs. 1 and 2, it will be perceived that one of the rocker arms 203 in each pair connected by a set of the toggle links 26 has an adjustable mechanical stop 32 interposed in its path of movement. In this instance, the stop 32 has a face 34 adapted to intercept face 35 of the adjacent gripping finger 2|. The stop 32 may be adjustably positioned at selected points along an arcuate path and in the illustrative cylinder this is achieved by means of a T-slot 3B and drawbolt 38. Various other arrangements including sliding wedges may, however, be employed for use in positioning the adjustable stop 32. By reason of the structure just described, when the gripping mechanism I8 is shifted from a fully disengaged position, shown in the righthand half of Fig. 1, to a fully engaged position, shown in the left-hand half of Fig. 1, the gripping finger of the rocker arm B associated with the adjustable stop 32 seats snugly against the stop face 34. By the same token, the free end portions of all the fingers 2! in the gripping mechanism seat snugly against the undercut end walls It of their respective pockets in the plate I2, placing the latter under considerable tension and locating it in a desired position of circumferential adjustment.

Since printing plates such as the plates I2 are normally made with a high degree of accuracy, the magnitude of the circumferential adjustment required to effect proper registration is relatively small. For the plate cylinder of an ordinary newspaper or magazine press, this range of adjustment may be on the order of approximately 1% measured along the peripheral surface of the plate cylinder. Notwithstanding its size, however, this factor must be taken into consideration in the design of the actuating elements of the gripping mechanisms I8. Accordingly, the inner end portion of each of the drawbolts 30 is anchored to the shaft I! through the use of a self-alining, thrust-resisting mounting. In the present instance, such mounting involves the use of a ball and socket arrangement, the inner end of each drawbolt being fashioned with a spherical enlargement 39 confined between an inner collar 40 and an outer collar 4|. Both of these collars are received within a recess 42 in the shaft H, the outer collar 41 being secured within such recess as by means of threads 44. Tapering gently outward from the spherical contour of its inner surface, the collar 4! is formed with a frusto-conical aperture 45 which provides clearance for limited angular movement of the drawbolt 39. This structure furnishes a floating mounting for the nut 29 of drawbolt 30 and permits sufficient shifting of the toggle link pivot 28 to accommodate the gripping mechanism in any one of its positions of adjustment as determined by the stop 32. Floating movement of the free end of the drawbolt is limited by means of an annular shoulder 45 formed in the cylinder [0 and disposed in spaced apart, surrounding relation with a bushing 48 freely journaled on the shank of the drawbolt 30.

In order to facilitate precise seating of respective ones of the gripping fingers 2| against their corresponding adjustable stops 32, and hence precise locating of each printing plate in various positions of circumferential adjustment, provision is made for overcoming the substantial frictional effect between the concave surface of each printing plate and the peripheral surface of the plate cylinder. This is accomplished by subjecting each of the gripping mechanisms I8 to a differential spring pressure which tends to bias such mechanism toward its adjustable stop 32. In this instance, there is operatively associated with the rocker arm 20A a loading spring 49 and with the rocker arm 203 a loading spring 59. The springs 49, 50 are respectively housed within threaded bores 5| running secantially of the plate cylinder body. Each of the springs is confined within its bore 5| by an axially movable thrust sleeve 52 and a threaded plug 54, the latter constituting a spring pressure adjusting means. Each of the sleeves 52 may be provided with a hemispherical projection 55 which bears against its associated one of the rocker arms 20A, 20B. In the practice of the invention, the spring 50 is adapted to exert a substantially greater force upon the rocker arm 2013 (which coacts with the adjustable stop 32) than the spring 49 is capable of exerting on the rocker arm 20A. Preferably, this is accomplished by forming the spring 50 with a substantially higher spring scale than the spring 49 although an adequate differential loading could also be created by suitable adjustment of spring tensions.

While the operation of the structure just described will doubtless be readily apparent to those skilled in the art, it might be helpful to outline the same briefly at this point. Starting with the gripping mechanism in a fully disengaged position as indicated in the right-hand half of Fig. 1, the cylinder I0 is rotated to a plate receiving position and a printing plate I2 is placed thereon over the disengaged gripping mechanism [8. Engagement between the latter and the arcuate end portions of the plate [2 is initiated by turning the drawbolt 30 in the proper direction to move the nut 29 in a generally radially outward direction. Due to the fact that the arm 20B is subjected to greater spring pressure than the arm 20A, the arm 20B will rock clockwise (as viewed in the right-hand side of Fig. 1). Since the arm 20B is connected to the pivot point 28 of the nut 29 by toggle link 26 which has a fixed dimension, the drawbolt 30 will be rocked in a counterclockwise direction about the center of its spherical end portion 39. By the same token, the link 26 connecting the arm 20A with the pivot on the nut 29 will also be rocked counterclockwise about its pivotal connection 25 on the end of the rocker arm 2A which temporarily remains fixed. This counterclockwise movement of the foregoing parts is eventually limited due to interception of the bushing 48 by the shoulder 46, the drawbolt 30 then occupying a position corresponding to that indicated inFig. 2. The net result of such movement thus far is to give the rocker arm 20B a substantial angular lead toward its fully engaged position, as compared with the rocker arm 20A. Further rotation of the drawbolt 30 in the same direction now results in angular movement of both of the arms 20A, 20B toward their engaged positions. Due to its angular lead, the arm 2013, through its gripping finger 2|, accosts the adjustable mechanical stop 32 before the arm 20A completes its angular movement. When this occurs, the pivot at the inner end of the arm 20B becomes fixed relative to the plate cylinder. Upon subsequent radial outward movement of the nut 29, the drawbolt and the toggle links 26 are rocked clockwise, as viewed in Fig. 1. This movement results in completion of the remaining angular displacement of the arm 20A and its associated connecting link 26, bringing the mechanism 18 to a fully engaged position as illustrated in the left-hand half of Fig. 1. During the course of their angular movement, the gripping fingers 2| of the rocker arms 20A, 20B enter into the pockets I4 of the printing plate and the finger for both arms make contact with the pocket end walls 16 very shortly before the arm 20A completes its angular displacement.

While the present invention is primarily concerned with circumferential adjustment of the plates I2, it should be noted that the structure thus far described also renders each of the plates susceptible of adjustment laterally of the cylinder l0. Such adjustment may, for example, be effected immediately prior to engagement of the gripping mechanism by tapping the side edges of the plate to move the same axially of the cylinder l0.

Referring now to Fig. 3, there is shown another illustrative plate cylinder IDA having modified gripping mechanisms [8A closely similar to the mechanisms l 8 described earlier herein but having a different form of adjustable stop means for defining the fully engaged position of the gripping mechanisms. In the following description of the modified mechanisms, new reference numerals will be applied only to parts peculiar to the same while the remaining parts will be identified by the numerals used earlier herein. In this instance, the stop abutment means for each gripping mechanism comprises an axially extending margin bar 56 of substantially T-shaped cross section, two such bars being mounted in substantially diametrically opposed relation for each pair of printing plates 12A. Each of the margin bars 56 is secured to the peripheral surface of the plate cylinder IDA as by means of a series of axially spaced screws 58 and is adjustable circumferentially thereof. To effect such circumferential adjustment, the bars 56 in this instance have elongated holes 59 terminating in head recesses 60 of comparable shape for receiving respective ones of the screws 58. Each of the margin bars is so proportioned that its overhanging lateral edges will overlie stepped arcuate edge portions GI, 64 of the printing plates !2A. In addition, each of the bars 56 is arranged so that one of its lateral edges will be susceptible of snug abutment with the radial surfaces of each plate edge portion Bl located adjacent the rocker arm 203 having the higher spring loading. The opposite lateral edge of each margin bar 56 is located so as to define a small clearance distance 62 between itself and the radial surfaces of plate edge portion 64 located adjacent the rocker arm 20A having the lighter spring pressure. By reason of the foregoing arrangement, individual circumferential adjustment of the plates IZA may be efiected simply by shifting the margin bars 56 circumferentially of the cylinder [0A and actuating the gripping mechanisms MA in the manner already described above.

I claim as my invention:

1. A tension lockup for the plate cylinder of a rotary printing press and comprising the combination of a pair of rocker arms having finger means susceptible of engaging undercut pockets in the respective circumferential extremities of an 'arcuate printing plate to place the same under tension, means including a common actuator for pivoting said rocker arms and their finger means in unison between engaged and disengaged positions relative to the plate, an adjustable mechanical stop disposed in the path of one of said rocker arms for interception thereof as said arm moves toward its engaged position, said stop being adapted to define the engaged position of both said rocker arms, and loading springs associated with respective ones of said rocker arms for urging the same toward their engaged position, the spring associated with said one rocker arm being of substantially greater strength than the spring associated with the other of said rocker arms.

2. In a plate cylinder for a rotary printing press, a tension lockup comprising the combination of a pair of rocker arms having finger means susceptible of engaging undercut pockets in the respective circumferential extremities of an arcuate printing plate to place the same under tension, means including a common actuator for pivoting said rocker arms and their finger means between engaged and disengaged positions relative to the plate, a circumferentially adjustable margin bar disposed in proximity to one of the circumferential edges of the plate for interception thereof, and loading springs associated with respective ones of said rocker arms for urging the same toward their engaged positions, the spring associated with said one rocker arm being of substantially greater strength than the spring associated with the other of said rocker arms so as to urge the one edge of the plate hard against said margin bar.

3. A tension lockup for the plate cylinder of a rotary press, said lockup comprising, in combination, a pair of rocker arms having finger means adapted for engagement with the respective circumferential extremities of an arcuate printing plate to place the same under tension, common actuating means including a toggle link connection for pivotally shifting said rocker arms and their finger means between engaged and disengaged positions relative to the plate, a circumferentially adjustable mechanical stop located adjacent one of said rocker arms, said stop being adapted to define the engaged position of both said rocker arms.

4. A tension lockup for the plate cylinder of a rotary printing press and characterized by the combination of an adjustable mechanical stop and a plate gripping mechanism having a fully engaged position defined by said adjustable mechanical stop, with differential loading spring means interposed between said gripping mechanism and said plate cylinder and adapted to bias said gripping mechanism against said adjustable mechanical stop and toward said fully engaged position.

5. A tension lockup for securing an arcuate printing plate to the plate cylinder of a rotary printing press and characterized by the combination comprising an adjustable mechanical stop, a pair of interconnected plate gripping elements engageable with the respective arcuate end portions of said plate, said elements having a fully engaged position defined by said adjustable mechanical stop, the latter being located in proximity to one said element, and a loading spring also located in proximity to said one element,

said loading spring being adapted to bias said one element in the direction of said adjustable mechanical stop.

6. A tension lockup for the plate cylinder of a rotary printing press and comprising the combination of a pair of circumferentially spaced movable abutments susceptible of engaging the arcuate end portions of a printing plate to place the same under tension, common actuating means for shifting said movable abutments between engaged and disengaged positions, an adjustable mechanical stop disposed for interception of one of said abutments as the same is moved toward its engaged position, and a pair of loading springs each associated with a respective one of said abutments, the loading spring of said one abutment being of substantially greater strength than the loading spring of the other of said abutments.

7. A tension lockup for securing an arcuate printing plate to the plate cylinder of a rotary press by placing the plate under tension circumferentially thereof, said lockup comprising the combination of a pair of circumferentially spaced movable abutments susceptible of engaging the arcuate end portions of the printing plate, common actuating means for shifting said movable abutments between engaged and disengaged po sitions, a mechanical stop adjustable circumferentially of the plate cylinder and disposed for interception of one of the arcuate edges of the printing plate as said abutments are moved into engagement with the plate, and a pair or loading springs each arranged to bear against a respective one of said abutments, the loading spring of said one abutment being of substantially greater strength than the loading spring of the other of said abutments.

8. A tension lockup for the plate cylinder of a rotary printing press and comprising the combination of a plurality of movable abutments susceptible of engaging the arcuate end portions of a printing plate to place the same under tension, common actuating means for shifting said movable abutments between an engaged and a disengaged position, a circumferentially adjustable mechanical stop disposed for interception of one of said abutments as the same is moved toward its engaged position, said adjustable mechanical stop being adapted to define the fully engaged position of all of said movable abutments, and a differential loading spring means adapted to bias said one abutment snugly against said adjustable mechanical stop.

9. A tension lockup for the plate cylinder of a rotary printing press and comprising the combination of a plurality of circumferentially movable abutments susceptible of engaging the arouate end portions of a printing plate to place the same under tension, common actuating means for shifting said movable abutments between an engaged and a disengaged position, a circumferentially adjustable margin bar disposed for interception of one of the arcuate edges of the printing plate as said abutments are moved toward a fully engaged position, and loading springs associated with certain ones of said movable abutments, said loading springs tending to bias said one arcuate edge of the rinting plate against said margin bar.

10. A tension lockup for the plate cylinder of a rotary printing press and comprising, in combination, a pair of rock shafts journaled Within the plate cylinder substantially parallel to the axis thereof, a first set or rocker arms fixed to one of said rock shafts for rotation therewith, a second set of rocker arms fixed to the other of said rock shafts for rotation therewith, each of said rocker arms having a finger portion susceptible of engaging a pocket in the underside of an arcuate printing plate, the fingers of said first set of rocker arms being adapted to engage pocket at one arcuate extremity of the plate, the fingers of said second set of rocker arms being adapted to engage pockets at the opposite arcuate extremity of the plate, common actuating means for moving said first and said second sets of rocker arms in unison between a disengaged position and an engaged position relative to the printing plate, an adjustable mechanical stop disposed for interception of one of the rocker arms in said first set as the same is shifted toward its engaged position, said stop being adapted to define various positions of engagement of all said rocker arms, and loading springs mounted in the plate cylinder and adapted to urge respective ones of said rocker arms toward their engaged position, the loading springs associated with said rocker arms in said first set being of substantially greater strength than those associated with the rocker arms of said second set.

11. A tension lockup for the plate cylinder of a rotary printing press and comprising, in combination, a pair of rock shafts journaled within the plate cylinder substantially parallel to the axis thereof, a first set of rocker arms fixed to one of said rock shafts for rotation therewith, a second set of rocker arms fixed to the other of said rock shafts for rotation therewith, gripping fingers on said rocker arms, the gripping fingers of said first set of rocker arms being adapted to engage pockets in the underside of one arcuate extremity of the plate, the fingers of said second set of rocker arms being adapted to engage pockets in the underside of the opposite arcuate extremity of the plate, common actuating means for moving said first and said second sets of rocker arms in unison between a disengaged position and an engaged position relative to the printing plate, a margin bar of substantially T- shaped cross section disposed in circumferentially adjustable relation on the plate cylinder for interception of the radial edge surface of the arcuate extremity of the plate gripped by said first set of rocker arms, and loading springs mounted in the plate cylinder and adapted to urge said rocker arms toward their engaged position, the loading springs associated with said rocker arms in said first set being of substantial- 1y greater strength than those associated with the rocker arms of said second set.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,731,662 Heinz Oct. 15, 1929 1,831,219 Wood Nov. 10, 1931 2,050,950 Huck Aug. 11, 1936 2,100,207 Wood Nov. 23, 1937 2,100,208 Wood Nov. 23, 1937 2,236,230 Worthington Mar. 25, 1941 2,428,263 Crafts Sept. 30, 1947 2,474,127 Tollison et a1. June 21, 1949 2,543,255 Parrish Feb. 27, 1951 

